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This paper proposes a new control scheme that is composed by the sliding mode control(SMC) with three-dimensional ceiling control to reduce the multi-dimensional vibration of the vehicle's seat. The seat suspension system is made of a kind of 3-RPS parallel mechanism, in which each limb is mainly composed by the spherical pair, spring, piston rod, damping fluid and rotary pair. Based on the single-open-chain theory, Position and Orientation Characteristics (POC) set of a 3-RPS seat mechanism was analyzed to verify its movement law. Three-dimensional seat system mathematical model was established, and the SMC and ceiling control were combined to obtain the required force. The ceiling control belongs to an ideal control method, it could provide the reference for the SMC. The comparisons between the SMC and passive seat suspension system were done when the vehicles were walking or working on E, F and G-roads. The results show that the transient amplitudes of seat acceleration outputs were reduced with the proposed control scheme. The research in this work can be extended and applied for other vehicles and improve their performance. [ABSTRACT FROM AUTHOR]

Customers' expectations for a consistent long-term high-level product performance have been increasing year after year, and the automotive industry is leading the trend. As an automotive seating component, polyurethane foam has a direct impact to the perceived value of an occupant, thus providing high durability foam became essential to customer satisfaction. Many tests were developed to evaluate the foam durability in various environments because of the importance of durability. The data used to correlate the results from these tests to that of foam collected from the used vehicles is limited because of the complex nature of aging and usage. In this study, newly manufactured foams were aged at a high temperature, and their fatigue properties were compared with the properties of foam samples collected from the vehicles of different mileage, age and geographical location. The results of this study showed that the heat aging at 100°C can be used to estimate the aging condition in a dry, hot climate with approximate mileage of 139,000 miles. However, varying the heated time of the foam for accelerated aging did not vary the fatigue property significantly enough to correlate to different mileage. Instead, an application of weight during the heating process is found to represent the fatigue property of foam at higher mileage than heat aging alone. Although the level of wear of the foam was found to be different depending on the environmental conditions, 25% compression load deflection (CLD) value before and after repeated compression of all samples of the same size were found to follow a logarithmic relationship. Further study of foam with different levels of wear are necessary for more detailed observations. [ABSTRACT FROM AUTHOR]

In general, cold-cured flexible foams have a high content of closed cells during a foaming process because of a high reactivity of foaming components and curing at a low temperature. Cold-cured flexible foams require a mechanical method such as roll crushing or vacuum crushing to open a high content of closed cells for preventing shrinkage and cracking of foam after demolding. But this mechanical crushing process can yield foams with poor properties and reduce productivity on account of increasing costs for utilities, electricity, manpower and repair. A noncrushing foam system developed by Kumho Mitsui Chemicals Inc. (hereafter referred to as "KMCI") is a new cell opening technology that makes complete cell opening during the foaming process. Thus, this technology results in no shrinkage and cracking after demolding. In addition the noncrushing foam system makes possible manufacturing automotive seat cushions having an open cell structure and excellent cell stability compared to conventional foam by minimizing the degree of cross-linking density and increasing urea linkage. Our new technology has been used to make seat cushion at Hyundai Motor Company in Korea since 1999. We expect that the noncrushing foam system will be applied in various flexible foam applications and will contribute to improvement of productivity and seat cushion quality. [ABSTRACT FROM AUTHOR]

Objective: To explore how individual characteristics influence selected lumbar support prominence (LSP), seated lumbar flexion, seatback average pressure, contact area, and center of pressure (CoP) location before and after 1 hr of driving. Background: An LSP can alter posture and may reduce low back pain during prolonged driving. Although LSP preference varies across individuals and may change over time, few investigations have explored the time-varying response to individually selected adjustable seat parameters. Method: Forty individuals selected LSP settings in an automotive seat through a series of systematic adjustment trials. The average LSP setting was fixed for a 1-hr driving simulation, followed by one final adjustment trial. Regressions were performed between individual characteristics and selected LSP, lumbar posture, and measures of seatback pressure from the initial adjustment trials. ANOVAs were performed to determine the effect of time and sex on these dependent variables. Discomfort was also monitored throughout the protocol. Results: Individual's standing lumbar lordosis, selected LSP, and height and mass were significant predictors for seated lumbar flexion, seatback average pressure, and contact area, respectively. Discomfort levels remained low; however, following the driving protocol, individuals altered their posture to decrease lumbar flexion and increase seatback average pressure without significant adjustments to the LSP. Conclusion: These findings highlight individual characteristics to consider in automotive seat design and that the method for determining LSP settings may facilitate appropriate LSP selection. Application: A systematic method to determine LSP settings may reduce discomfort and automate seat adjustments, such that only short-term postural adjustments may be required. [ABSTRACT FROM AUTHOR]

Vehicle seat suspension is one of very important components to provide ride comfort, in particular, commercial vehicles, to reduce driver fatigue due to long hours driving. This paper presents a study on active control of seat suspension to reduce vertical vibration transmitted from uneven road profile to driver body. The control problem will be firstly studied by proposing an integrated seat suspension model which includes vehicle chassis suspension, seat suspension, and driver body model. This is a new concept in the field of study because most of the current active and semi-active seat suspension studies only consider seat suspension or seat suspension with human body model, and road disturbance is generally assumed to be applied to the cabin floor directly. Controller design based an integrated model will enable the seat suspension to perform in a scenario where vibration caused by road disturbance is transmitted from wheel to seat frame and ride comfort performance is evaluated in terms of human body instead of seat frame acceleration. A static output feedback controller is then designed for the seat suspension with using measurement available signals. Driver mass variation and actuator saturation are also considered in the controller design process. The conditions for designing such a controller are derived in terms of linear matrix inequalities (LMIs). Finally, numerical simulations are used to validate the effectiveness of the proposed control strategy. It is shown from the driver body acceleration responses under both bump and random road disturbances that the newly designed seat suspension can improve vehicle ride comfort regardless of driver body mass variation. [ABSTRACT FROM AUTHOR]

This study proposes a methodology that enables the comparison of textile materials from the point of view of corresponding comfort. Although this study focuses on textile materials used for the construction of car seats, the approach can be used more broadly. First, different aspects, which are more or less closely connected with our problem, are discussed. Among them, two characteristics, i.e. temperature conductivity and breathability, are important. Second, we discuss why it is important to have conclusions about comfort based not only on the subjective feelings of evaluators, but also on objective measurements. To that purpose, an experiment and a questionnaire summarising subjective feelings are proposed and concisely described. Furthermore, the choice of sensors, their placement in a car seat and the manner of recording data are discussed. Finally, the choice of appropriate statistical methods suitable for the analysis of collected data is discussed. The approach is illustrated via real experiments. Our findings support the current trend that the use of 3D spacer fabrics improves both breathability and sitting comfort in general. [ABSTRACT FROM AUTHOR]

The main motive for this research is the desire for the improvement of the automotive seat occupant's comfort by designing a heating mat prototype made with distance knitting technology with heating elements. In this study, the following design steps were undertaken: preparation of the trajectories of heating cables, calculating the resistance needed to obtain the estimated power of the whole mat, testing of available electroconductive yarns to assign the most suitable yarn to a specific design, preparation and testing of five heating mat prototypes with three various trajectories of the heating element. All samples were evaluated with the same criteria in order to find the most promising design. After all experiments, a prototype with stainless-steel Bekaert® VN 12.2 coated yarn as a heating element, showed the best performance, especially in combination with distance knitted fabric thanks to its internal construction. This work demonstrates that a three-dimensional distance knitted fabric with a heating element introduced into its structure will ensure the physiological sitting comfort. After further subsequent studies, the proposed method can be adapted for industrialisation by using warp knitting machines, thus improving the quality and durability of the heating mat. [ABSTRACT FROM AUTHOR]

Improving the comfort and durability properties of automotive seating is an increasingly important issue within the global automotive seating industry. The technology for enhancing the comfort properties of polyurethane foams is one of the major needs of seating foam manufacturers and seat producers, whose focus is both foam density reduction and overall weight reduction of car seats. Shell Chemicals has therefore embarked on a fundamental program, focusing on the foam formulation-durability relation of TDI-based foam grades. The study consists of a thorough investigation of the influence of independent formulation variables such as raw materials composition, water level and ancillary chemicals levels on foam processing and durability performance. A statistics driven experimental approach (central composite and full factorial designs) helped to increase the predictive power of the outcome, concerning overall mechanical foam properties and comfort performance in particular. [ABSTRACT FROM AUTHOR]

In this work, the dedicated test stand was applied to investigate the human body–vehicle seat system. The particular signals were measured by accelerometers placed on the seat and the human head. The horizontal vibrations were applied as the input to the system. As an alternative to the classical Fourier approach, the wavelet transfer function was introduced to describe the effectiveness of particular seat suspension. The human head reaction was investigated as the system output. [ABSTRACT FROM AUTHOR]

A 2006 US copycat crime wave came into being, surged with thousands of crimes committed, and dissipated without substantial news media attention. The development of this early copycat crime meme is traceable to the nature of the crime, "ghost riding the whip," and the social media and popular music communication channels associated with it. Ghost riding the whip involved traffic violations where drivers exit their cars and dance atop or alongside the moving driverless vehicles. Social media allowed the widespread diffusion of detailed instructions that spread this crime from a single minority community to the middle class within a 3-month period. The study of this copycat crime meme examined four types of data: Google Trends, rap songs, ProQuest news media data, and YouTube videos. The examination of the crime wave suggests how Gabriel Tarde's 19th-century ideas operate in the contemporary social media era. However, unlike pre-social media-based crime waves that were launched via interpersonal and legacy media communication pathways, for ghost riding, rap songs, YouTube postings, and Google searches spurred its growth. Legacy media were found to be most important during the crime wave's decline, but not during its diffusion. For this copycat crime meme, social media's influence flowed in a unique upward and outward pattern and the results raise the research questions as to how social media have changed the dynamics of crime waves and how important legacy media will be in future crime waves. [ABSTRACT FROM AUTHOR]

Objective: The aim of the current study is to examine the influence of static factors on overall seating comfort in motorcycles and validate the use of static lab-based setups for evaluating seating comfort in motorcycles.Background: Seating comfort in automobiles has two factors, static and dynamic. Research on seating comfort of passenger cars has shown that when the magnitude of vibration reaching the seat is low, comfort is largely determined by static factors. Studies have also validated the use of static lab-based setups for research on seating comfort in passenger cars. Static lab-based setups are easy to develop, provide a controlled environment, and efficient for experimental research. The riding posture, mass distribution, and dynamics of a motorcycle differ from a passenger car and warrant further investigation to extend the results from the research on passenger cars.Method: The study compares subjective rating of seating comfort and objective measurement of seat interface pressure in two test conditions: a static lab-based setup and actual driving on a flat test track where the magnitude of vibration reaching the seat is low. The vibration at the seat is measured for the driving trial. A group of 18 male volunteers from TVS Motor Company participated in the study, and two motorcycles from the economy/executive segment of India are used in the study. The subjective ratings are analyzed statistically using analysis of variance (ANOVA) and Pearson's correlation. The vibration data are analyzed as per ISO 2631-1 to calculate the frequency-weighted acceleration, aw.Results: The results show that there is no significant difference between the two test conditions either in the objective measurements or in the subjective rating of comfort. There is also a statistically significant correlation between the subjective ratings of seating comfort in static lab-based setup and actual riding (r = .77, p < .01, n = 36). The mean aw at the seat while driving in the test track used in this study is 0.2 m/s2.Conclusion: Static factors have a significant influence on seating comfort in motorcycles. When the vibration reaching the seat is low (aw ≤ 0.2 m/s2), seating comfort is largely determined by the static factors. The use of static lab-based setups for evaluating static factors of seating comfort in motorcycles is validated.Application: The results of this study enable further research to understand the human criterion for seating comfort in motorcycles using static lab-based setups which are easier to develop and provide controlled environment that is essential for any research. [ABSTRACT FROM AUTHOR]

Objective The effects of seat height and anthropometric dimensions on drivers' preferred postures were investigated using a multiadjustable vehicle mock-up with a large number of adjustments and extended ranges. Background Many studies have been conducted on preferred driving posture under different test conditions showing mixed and even contradictory findings. No studies thus far have considered the clutch and compared Chinese and European drivers. Method Four seat height conditions were tested: free and three imposed heights (250, 300, and 350 mm). Sixty-one subjects (40 French-born and 21 Chinese-born) participated in the experiment, covering a large range of stature and sitting height-to-stature ratio. The RAMSIS kinematic model was used to reconstruct postures, and main intersegmental angles were extracted for characterizing posture. Results Under the free seat height condition, no significant differences in preferred intersegmental angles were observed between different participant groups. Seat height mainly affected trunk-thigh angle, whereas it had almost no effect on trunk orientation and other intersegmental angles. Chinese participants sat more forward in the seat, leading to a more opened trunk-thigh angle and a more reclined trunk. Conclusions Results suggest that intersegmental angles of preferred posture are not dependent on anthropometric dimensions, although shorter drivers prefer a slightly less reclined trunk. Self-selected driving posture results from a compromise between maintaining the intersegmental angles in one's preferred range and a preferred trunk orientation in space. Applications The findings contribute to a better understanding of preferred driving postures and would be helpful for improving vehicle interior design. [ABSTRACT FROM AUTHOR]

The ride comfort of a vehicle is a vital aspect determining competitiveness of vehicles. The comfort is intricately related to feelings of discomfort due to vibration. The discomfort depends on various dynamic aspects of the suspension-seat and surrounding system. In industry, the discomfort due to vibration is assessed by road testing on various surfaces; these road tests may not be accurately repeatable. Discomfort, in general, can be assessed by measurements based on a shaker table and seat combination. These results when used for "in vehicle situations" may not accurately indicate the level of human discomfort in a vehicle. In view of this, to quantify seated human discomfort in a vehicle, measurements were performed using a four-post rig simulator; the setup allows controlled in-situ experiments to be conducted. A group of six subjects were exposed to sinusoidal vibration at five magnitudes in the vertical direction for heave, roll and pitch motion. The objective is to develop a discomfort metric which could be used to compare vehicles. The preliminary results show varying significance of roll, pitch and heave motion. The results, however, confirm the nonlinear variation of perception as a function of the physical stimulus. The test setup can be used to study the effects of complex road inputs and eventually may contribute towards reduced reliance on road tests. [ABSTRACT FROM AUTHOR]

Objective: This article describes a new and more repeatable, reproducible, and valid test method for characterizing lumbar support in automotive seating. Background: Lumbar support is important because it affects occupant accommodation and perceptions of seat comfort. Assessing only the lumbar mechanism-particularly in terms of travel-is inadequate because it does not consider the effects of trim and foam. Method: The Society of Automotive Engineers' next-generation H-Point machine and associated loading protocol were used as the basis for the new test. Results: The method was found to satisfy minimum gage repeatability and reproducibility requirements. Validity was demonstrated through a regression model that revealed 93.9% of the variance in subjective ratings of poor uncomfortable lumbar support can be explained by two objective indicators: (1) lumbar support prominence in the full-off position and (2) effective travel. Conclusion: The method can be used to differentiate between seats offering two-way adjustable lumbar support. The best two-way adjustable lumbar seat systems are those that couple little to no lumbar support in the starting or off position (i.e., they are nonintrusive) with a considerable amount of effective or perceptible travel. Application: The automotive industry has long needed a way to address the fact that consumers want more lumbar support than their seats currently supply. This contribution offers a method to objectify an important aspect of automotive seating comfort-namely, lumbar support. This should help human factors professionals produce, but not necessarily guarantee, better consumer ratings. [ABSTRACT FROM AUTHOR]